Fictitious viewport for position: fixed

This bug applies to Chrome 48 on Android. It was possibly introduced in Chrome 40, together with the change in position: fixed behaviour.
I can confirm its presence in Chromium 44.

In affected browsers the red layer at the bottom of the screen is invisible. However, this test script
makes it appear at (or just below) the bottom of the screen.

Please reload this page after changing the orientation.

This element is px wide.

This page has a standard meta viewport. The actual layout viewport dimensions are . It also contains an element
that’s wider than the actual layout viewport; it has width: 120%.

However, in affected browsers a position: fixed layer is positioned as if the actual layout viewport is
pixels high — the height of a fictitious viewport as wide as the wide element and with the
same aspect-ratio as the layout (or visual) viewport. Usually this will render it invisible.

Test: the difference between the desired and actual position should be . If we set
bottom: px on the fixed layer, it should appear just at the bottom of the actual layout viewport.
That’s what the test script above does.